J-aggregate fluorescence probe constructed based on AIE units for analysis of Zn, Cu ions in food and biological systems.

The precise detection of metal ions is crucial in food safety, biomedical diagnostics, and environmental monitoring. Although traditional "on-off" fluorescence probes are frequently utilized, their anti-interference capability remains a limitation. This study synthesized three new copper-based fluorescent probes: PTA, PTP, and PTD. Among them, PTD exhibited unique aggregation-induced emission (AIE) properties. PTD's remarkable selectivity for Zn was due to the formation of Zn-induced J-aggregates, which resulted in a concentration-dependent fluorescence redshift from green to yellow and then to red. Additionally, PTD demonstrated a rapid and sensitive response to Cu, and it was successfully integrated into a smartphone-based platform for the semi-quantitative detection of Zn and Cu in real food samples. The effectiveness in biological applications was also validated through live-cell imaging tests. This work contributes to the creation of highly selective and interference-resistant ratiometric fluorescence sensors by leveraging the special process of target metal ion-induced J-aggregate production in AIE-based probes.